An insert mailer may require a window die cut
on the front of the outgoing mailer if an area of the insert must be imprinted
with an original image rather than a transferred image. Imprinting on membership
cards and OCR scanning are examples of when an original image imprint would
be required.

Die cutting is also applied to the mailer during
the collating of it and is part of the construction process. The area
between one insert and the next on the roll is die cut out and discarded.

It is necessary to die cut the area
between inserts out so that the insert does not interfere with the
cross web gluing and so that the insert will fit within the mailer.
The area that is die cut and removed is called the chip. The end cut
of the chip can be produced as a slit on the press or it can be produced
on the collator. When there are several inserts in the mailer, they
are run through together so the die cutting is completed on all of
them at the same time.